New candidate JEP: 357: Migrate from Mercurial to Git

[Joe Darcy]

Hello,

Responding to a few points below,

On 7/16/2019 5:19 AM, Severin Gehwolf wrote:
> Hi Aleksey,
>
> Source control discussions tend to be very opinionated. I'm not sure
> all arguments can be objectively answered let alone quantified. Please
> keep that in mind when reading my comments below. Again, as said
> elsewhere, I'm biased towards Git.
>
> On Mon, 2019-07-15 at 20:52 +0200, Aleksey Shipilev wrote:
>> On 7/15/19 7:54 PM, mark.reinhold at oracle.com wrote:
>>> https://openjdk.java.net/jeps/357
>> Unfortunately, this JEP only discusses the advantages, and does not discuss the disadvantages of
>> performing this move.
> Should this JEP go into the details of advantages/disadvantages of HG
> vs. Git itself? I wouldn't think so, but your mileage may vary.
>
>> The disadvantages, off the top of my head:
>>   *) Conversion takes time and effort for all projects, including those developed outside of
>> mainline: Amber, Loom, Panama, Portola, Shenandoah, Valhalla to name a few;
> I think many of those have been converted already for somebody to take
> a look:
>
> Amber: https://github.com/openjdk/amber
> Shenandoah: https://github.com/openjdk/shenandoah
> Panama: https://github.com/openjdk/panama
> Portola: https://github.com/openjdk/portola
> Valhalla: https://github.com/openjdk/valhalla
> Loom: https://github.com/openjdk/loom
>
> Perhaps it would be reasonable to provide some info on how those
> repositories got converted and how much time it to to convert them.
> This would allow involved parties to ball-park estimate their up-front
> conversion work.


I didn't run the conversions myself, but I believe each one took on the 
order of a few hours. FYI, the code that did the conversion is part of 
the published Skara tooling:

     https://github.com/openjdk/skara

As this conversion is mostly a one-time process, I don't regard the 
conversion time as a major factor. It would likely be quicker for down 
stream users to clone fresh from git as opposed to running the 
conversion process independently.

The intention of the converted repos listed above, and the other ones 
under https://github.com/openjdk, is to let developers using the 
Mercurial versions of the OpenJDK repos in question have a low-friction 
way to kick the tires on a git version of a project of interest.

HTH,

-Joe